Turnagain Pass Avalanche Forecast RSS

Archives
ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sat, January 12th, 2013 - 7:00AM
Expires
Sun, January 13th, 2013 - 7:00AM
Forecaster
Kevin Wright
Avalanche risk The Bottom Line

Persistent deep slab problems are lingering in the backcountry.   The CONSIDERABLE danger rating above treeline is for a low likelihood but very high consequence avalanche problem.   Recent avalanche activity, both natural and human triggered, gives us enough evidence to call the backcountry dangerous right now.   The danger will be increasing this weekend as a large weather system moves in this afternoon.

Thanks to our sponsors!
Sat, January 12th, 2013
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
Moderate (2)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Considerable (3)
Treeline
1,000'-2,500'
Avalanche risk
Moderate (2)
Below Treeline
Below 1,000'
Avalanche risk
Moderate (2)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Deep Persistent Slabs
    Deep Persistent Slabs
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
More info at Avalanche.org

The deep slab problem is still our primary concern in the backcountry.  Remember, besides being a deep slab, it’s also a persistent weak layer.  This means the problem is not going away quickly.  The trend for a problem like this is to take a long time for stability to improve in the absence of provoking weather.  Natural avalanches will become more likely as new precipitation starts today, which also makes human triggered avalanches more likely.  The size of expected avalanches remains very large and destructive.

Recent avalanche activity in our region includes the large snowmachine triggered slide on Seattle ridge, and the similar slide in Main Bowl on Tuesday.  Explosive triggers brought down large avalanches on Wednesday with crowns 10-15 feet deep.

Yesterday in snowpit testing we found the relatively deep and heavy snowpack is still reactive on the facets at the ground interface.  Pit tests show disconcerting results with easy failure on isolation and a significant collapsing of the weak layers.  This means that although it will be difficult for a person to initiate the collapse through the deep and strong slab layer, if a collapse begins the resulting avalanche will likely propagate, pull the entire depth of the snowpack, and become very large and destructive.

Careful routefinding will be important this weekend.  Steep slopes should be avoided.

Repeat Offender avalanche 1-8-13

Avalanche Problem 2
  • Wind Slabs
    Wind Slabs
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

Recent wind above 2000 feet showed scoured ridges in some areas of Turnagain Pass.  Isolated pockets of stiffer wind slabs should be expected if you travel up the ridges above treeline. 

Weather
Sat, January 12th, 2013

The last couple days have brought generally good weather to our region.   A change is coming this weekend with expected warming, rain, and snow.

We expect an increase in the avalanche danger correlated to this weather event, with the intensity expected to peak Sunday-Monday.   For today, the beginning of this storm system will move in, with a mild increase in the avalanche danger associated with the weather event by this evening.

NWS graphic

Observations
Recent Observations for Turnagain Pass
Date Region Location
05/21/22 Turnagain Avalanche: Magnum, Lipps and Tincan
05/17/22 Turnagain Avalanche: Sunburst
05/17/22 Turnagain Observation: Tincan Ridge
05/11/22 Turnagain Avalanche: Cornbiscuit and Magnum west faces
05/07/22 Turnagain Observation: Granddaddy
04/29/22 Turnagain Observation: Sunburst wx station
04/28/22 Turnagain Observation: More Turnagain Pass/Summit Lake wet slab activity
04/27/22 Turnagain Observation: Magnum
04/27/22 Turnagain Observation: Girdwood/Summit/Turnagain Road obs
04/24/22 Turnagain Avalanche: Seattle Ridge – large glide avalanche on Repeat Offender path
Riding Areas
Updated Fri, May 13th, 2022

Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: mailroom_r10_chugach@fs.fed.us

Area Status Weather & Riding Conditions
Glacier District
Johnson Pass
Closed
Closed as of May 1 per Forest Plan.
Placer River
Closed
Closed as of April 25th due to insufficient snow coverage.
Skookum Drainage
Closed
Closed as of April 1st per Forest Plan.
Turnagain Pass
Open
Open. Extended opening through May 31.
Twentymile
Closed
Closed as of April 6th due to insufficient snow coverage.
Seward District
Carter Lake
Closed
Closed as of May 1 per Forest Plan.
Lost Lake Trail
Closed
Closed as of May 1 per Forest Plan.
Primrose Trail
Closed
Closed as of May 1 per Forest Plan.
Resurrection Pass Trail
Closed
Closed as of May 1 per Forest Plan.
Snug Harbor
Closed
Closed as of May 1 per Forest Plan.
South Fork Snow River Corridor
Closed
Closed as of May 1 per Forest Plan.
Summit Lake
Closed
Closed as of May 1 per Forest Plan.

Subscribe to Turnagain Pass
Avalanche Forecast by Email

This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.